Autonomous engine health management system

ABSTRACT

An engine health monitoring system includes an engine component having a sensor system configured to monitor at least one parameter of the component. An autonomous monitoring system is coupled to the sensor system and is configured to receive and store the at least one monitored parameter while an engine controller is unpowered. The engine controller is communicatively coupled to the autonomous monitoring system.

TECHNICAL FIELD

The present disclosure relates generally to turbine engine healthmanagement, and more specifically to an autonomous monitoring system forthe same.

BACKGROUND

Gas turbine engines, such as those used in commercial and militaryaircraft, include multiple moving components. In order to prevent damageto the moving components a lubricant and coolant, such as oil, isprovided to the moving components. In some example engines, thecomponents can be subjected to wind milling, or other motion, while theengine is off. If insufficient lubrication is provided to the movingcomponents while the engine is off, the engine can sustain damage in amanner that is not readily apparent until a failure mode is exhibitedduring operation.

Monitoring systems incorporated into the engine controller, such as aFull Authority Digital Engine Controller (FADEC), monitor the operationof the moving components while the engine is on. However, typical enginecontrollers draw power from onboard power generation and power down whenthe aircraft is not in operation. As the engine controller is powereddown while the engine is not in operation in these examples, the enginecontroller is incapable of monitoring the moving components or thelubrication systems while the engine is powered down.

SUMMARY OF THE INVENTION

In one exemplary embodiment an engine health monitoring system includesan engine component including a sensor system configured to monitor atleast one parameter of the component, an autonomous monitoring systemcoupled to the sensor system and configured to receive and store the atleast one monitored parameter while an engine controller is unpowered,and the engine controller is communicatively coupled to the autonomousmonitoring system.

In another exemplary embodiment of the above described engine healthmonitoring system, the autonomous monitoring system includes a powersource configured to provide operational power to the autonomousmonitoring system.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the power source is connected to an on-boardgenerator of an aircraft.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the power source includes an input configuredto be connected to a ground based power supply.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the sensor system is communicatively coupledto the engine controller.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the engine component includes a bearing oilsupply, and the sensor system includes an inlet pressure sensor.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the sensor system includes an ambientpressure sensor.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the inlet pressure sensor and the ambientpressure sensor are the same sensor.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the engine component includes a shaft and thesensor system includes a rotational speed sensor configured to detect arotational speed of the shaft.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the autonomous sensor system includes a localmemory, a local processor and a local power storage device, the localprocessor being configured to receive sensor data from the sensorsystem, correlate the received sensor data with a time at which thesensor data was generated, and store the sensor data in the localmemory.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the local processor is further configured topre-process the received sensor data and determine the occurrence ofpotentially damaging conditions.

In another exemplary embodiment of any of the above described enginehealth monitoring systems, the autonomous sensor system is furtherconfigured to communicate stored sensor data to the engine controllerduring an engine initialization.

An exemplary method of monitoring the health of a gas turbine engineincludes sensing at least one of an inlet oil pressure and a shaft speedwhile a gas turbine engine is off, storing the sensed values of the atleast one of an inlet oil pressure and a shaft speed in a local memoryof an autonomous monitoring system, and reporting the stored sensedvalues of the at least one of the inlet oil pressure and the shaft speedto an engine controller during an engine initialization.

Another example of the above described method of monitoring the healthof a gas turbine engine further includes analyzing the reported storedsensed values using the engine controller during an initialization ofthe engine, and halting the initialization of the engine in response toa determination that at least one component operated in a potentiallydamaging condition based on the sensed values.

Another example of any of the above described methods of monitoring thehealth of a gas turbine engine further includes the engine controllerdetermining that a shaft operated in a potentially damaging condition inresponse to a sensed rotational shaft speed exceeding a maximumthreshold while the engine is off.

Another example of any of the above described methods of monitoring thehealth of a gas turbine engine further includes the engine controllerdetermining that a shaft operated in a potentially damaging condition inresponse to a sensed inlet oil pressure falling below a minimumthreshold while the engine is off.

Another example of any of the above described methods of monitoring thehealth of a gas turbine engine further includes charging a local powerstorage device of the autonomous monitoring system while the engine isoperating.

Another example of any of the above described methods of monitoring thehealth of a gas turbine engine further includes correlating the storedsensed values of the at least one of an inlet oil pressure and a shaftspeed with a time at which the value was sensed using a local processorof the autonomous monitoring system, and storing the time correlation inthe local memory.

Another example of any of the above described methods of monitoring thehealth of a gas turbine engine includes reporting the stored sensedvalues of the at least one of the inlet oil pressure and the shaft speedto the engine controller during an engine initialization furtherincludes reporting the time correlated to the engine controller.

These and other features of the present invention can be best understoodfrom the following specification and drawings, the following of which isa brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an exemplary gas turbine engine.

FIG. 2 schematically illustrates an exemplary autonomous monitoringsystem for a gas turbine engine.

FIG. 3 illustrates an autonomous monitoring process of an exemplary gasturbine engine.

DETAILED DESCRIPTION OF AN EMBODIMENT

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flow path B in abypass duct defined within a nacelle 15, while the compressor section 24drives air along a core flow path C for compression and communicationinto the combustor section 26 then expansion through the turbine section28. Although depicted as a two-spool turbofan gas turbine engine in thedisclosed non-limiting embodiment, it should be understood that theconcepts described herein are not limited to use with two-spoolturbofans as the teachings may be applied to other types of turbineengines including three-spool architectures. It should be furtherunderstood that some or all of the following concepts can be applied togas turbine engines other than geared turbofan based engines withminimal or no modifications.

The exemplary engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beprovided, and the location of bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a first (or low) pressure compressor 44 and afirst (or low) pressure turbine 46. The inner shaft 40 is connected tothe fan 42 through a speed change mechanism, which in exemplary gasturbine engine 20 is illustrated as a geared architecture 48 to drivethe fan 42 at a lower speed than the low speed spool 30. The high speedspool 32 includes an outer shaft 50 that interconnects a second (orhigh) pressure compressor 52 and a second (or high) pressure turbine 54.A combustor 56 is arranged in exemplary gas turbine 20 between the highpressure compressor 52 and the high pressure turbine 54. A mid-turbineframe 57 of the engine static structure 36 is arranged generally betweenthe high pressure turbine 54 and the low pressure turbine 46. Themid-turbine frame 57 further supports bearing systems 38 in the turbinesection 28. The inner shaft 40 and the outer shaft 50 are concentric androtate via bearing systems 38 about the engine central longitudinal axisA which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 whichare in the core airflow path C. The turbines 46, 54 rotationally drivethe respective low speed spool 30 and high speed spool 32 in response tothe expansion. It will be appreciated that each of the positions of thefan section 22, compressor section 24, combustor section 26, turbinesection 28, and fan drive gear system 48 may be varied. For example,gear system 48 may be located aft of combustor section 26 or even aft ofturbine section 28, and fan section 22 may be positioned forward or aftof the location of gear system 48. Alternative engine types, such asdirect drive engines can omit the fan drive gear system 48 entirely, andconnect the fan 42 directly to one of the low speed spool 30 and thehigh speed spool 32.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than about ten (10), thegeared architecture 48 is an epicyclic gear train, such as a planetarygear system or other gear system, with a gear reduction ratio of greaterthan about 2.3 and the low pressure turbine 46 has a pressure ratio thatis greater than about five. In one disclosed embodiment, the engine 20bypass ratio is greater than about ten (10:1), the fan diameter issignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 has a pressure ratio that is greater thanabout five (5:1). Low pressure turbine 46 pressure ratio is pressuremeasured prior to inlet of low pressure turbine 46 as related to thepressure at the outlet of the low pressure turbine 46 prior to anexhaust nozzle. The geared architecture 48 may be an epicycle geartrain, such as a planetary gear system or other gear system, with a gearreduction ratio of greater than about 2.3:1. It should be understood,however, that the above parameters are exemplary of one embodiment of ageared architecture engine and that the present invention is applicableto other gas turbine engine architecture including direct driveturbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8 Mach andabout 35,000 feet (1066.8 meters). The flight condition of 0.8 Mach and35,000 ft (1066.8 m), with the engine at its best fuel consumption—alsoknown as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—isthe industry standard parameter of lbm of fuel being burned divided bylbf of thrust the engine produces at that minimum point. “Low fanpressure ratio” is the pressure ratio across the fan blade alone,without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressureratio as disclosed herein according to one non-limiting embodiment isless than about 1.45. “Low corrected fan tip speed” is the actual fantip speed in ft/sec divided by an industry standard temperaturecorrection of [(Tram ° R)/(518.7° R)]̂0.5. The “Low corrected fan tipspeed” as disclosed herein according to one non-limiting embodiment isless than about 1150 ft/second (350.5 m/s).

Certain components within the gas turbine engine, such as journalbearings or other bearing types, require lubrication or cooling any timethe component moves. Movement of the component without adequatelubrication or cooling can result in damage that is not detected untilthe engine 10 enters a failure mode during operation. Further, certainof these components are connected to the fan 42 either through a gearingsystem or directly. When an aircraft is not in operation, but ispositioned outside, environmental conditions such as wind can cause thefan 42 to rotate. This rotation is referred to as wind milling. Due toits connection to one or more shafts within the engine, when the fanbegins wind milling, components within the engine are rotated.

In order to monitor the engine systems, and detect conditions that couldlead to hidden damage within the engine systems, an autonomousmonitoring system is incorporated in the engine 20.

FIG. 2 schematically illustrates an exemplary engine health monitoringsystem 100 that is capable of monitoring for wind milling and monitoringengine systems during wind milling while the engine is in an off state.Included within the gas turbine engine systems is a shaft 110. The shaft110 is supported by one or more bearings 120. In some examples, thebearings 120 are journal bearings. In alternative examples, alternativebearing types may be utilized in place of, or in addition to, journalbearings. Rotation of the shaft at speeds in excess of an maximum speedthreshold while the engine is off can result in undetected damage andcause the engine to enter a failure mode during operation of the gasturbine engine.

An oil based lubricant is provided to the bearings 120 from an oil inlet130. In some examples, the oil can be provided as a spray 132. Inalternative examples, such as with journal bearings, alternative oildelivery means or mechanisms can be utilized to the same effectdepending on the physical construction of the bearing 120 and the gasturbine engine 20. Oil is provided to the oil inlet 130 via an oil line134 connected to a pump 140. The pump 140 is in turn connected to an oilsupply 150, and draws oil from the supply 150. The pump 140 maintains athreshold inlet oil pressure at the inlet 130. As long as the oil inletpressure stays at, or above, the threshold inlet oil pressure, the shaft110 can rotate within the bearing 120 without causing damage to thebearing 120 or the shaft 110. Rotation of the shaft while the oil inletpressure is below the threshold can cause undetected damage that canresult in the engine entering a failure mode during standard operations.

The exemplary engine health monitoring system 100 includes a shaft speedsensor 160 connected to the shaft 110 and capable of detecting arotational speed of the shaft 110. Also included is an inlet oilpressure sensor 170 capable of detecting the pressure at the oil inlet130. In some examples, the inlet oil pressure sensor 170 is also capableof detecting an ambient atmospheric pressure at or near the oil inlet130. While illustrated and described herein as individual sensors 160,170, one of skill in the art will understand that each of the sensors160, 170 can be a network of individual sensors configured tocooperatively determine a corresponding sensed parameter or parameters.

During operation of the engine 20, data from each of the sensors 160,170 is provided to an engine controller 180. The engine controller 180can be a full authority digital engine controller (FADEC) or any othertype of engine controller. The engine controller 180 also includes apower input 182 connected to an on-board power supply of the gas turbineengine. In some examples, the on board power supply is a generatorconfigured to generate electrical power utilizing the rotation of theshaft within the gas turbine engine.

Due to being receiving power from on board power supply, the enginecontroller 180 does not operate while the engine is shut down. As thecontroller 180 is not operating, the controller 180 cannot receive andmonitor sensor values from the sensors 160, 170 and the enginecontroller 180 cannot detect the occurrence of wind milling. Similarly,the controller 180 cannot detect the occurrence of potentially damagingconditions or events that occur as the result of wind milling.

The engine health monitoring system 100 also includes an autonomoussensor system 190. The autonomous sensor system 190 includes a localmemory 192 and a local processor 194. Also included within theautonomous sensor system 190 is a power storage device 196. The powerstorage device 196 includes an input 198 connected to the same on boardpower supply and the power input 182 of the engine controller 180. Inalternative examples, the input 198 is connected to an alternative onboard power generation system. In yet further alternative examples, theinput 198 can be connected to a ground based power supply via a standardpower supply interface.

In examples using the ground based power supply, the power storagedevice 196 can be omitted and the autonomous sensor system 190 can bepowered directly from the ground based power supply.

As the autonomous sensor system 190 has operational power from the powerstorage element 196, the autonomous sensor system 190 is capable ofmonitoring data from the sensors 160, 170 while the engine is off. Datafrom the sensors 60, 170 is time correlated by the local processor 194and stored in the local memory 192 of the autonomous sensor system 190.When the engine is turned on again, power is provided to the enginecontroller 180, and the engine controller 180 begins engineinitialization.

As a part of the engine initialization process, the controller 180retrieves the stored data from the autonomous sensor system 190. Thecontroller 180 can then analyze the data and determine if any windmilling or potentially damaging events occurred during the period inwhich the engine was off. If any of these events occurred, thecontroller 180 can respond in a pre-defined manner. In some examples,when the controller 180 determines that a potentially damaging eventoccurred, the controller 180 stops initialization of the engineentirely, and sends an error message indicating that the engine mustundergo maintenance before the engine can be initialized.

In some examples, the above described analysis can be performed in wholeor in part at the local processor 194 within the autonomous sensorsystem 190. In these examples, the local processor 194 then creates alog of events to be reviewed by the engine controller 180 duringinitialization. In this way the length initialization process of theengine can be reduced as the engine controller 180 only considers alimited amount of data.

In further examples, the engine controller 180 can analyze the dataduring initialization for gaps indicating that the autonomous sensorsystem 190 was unpowered or otherwise unable to monitor the sensors 160,170 for a time period while the engine was off. If the engine controller180 detects such a time period, the engine controller 180 can determineif the gap exceeds a minimum time threshold. If the minimum timethreshold is exceeded, the engine controller 180 can refuse toinitialize the engine until after maintenance has occurred.

With continued reference to FIG. 2, FIG. 3 illustrates a method foroperating the engine health monitoring system 100 of FIG. 2. Initially,the engine controller 180 begins an engine shutdown sequence at an“Engine Shutdown Begins” step 210. Prior to the engine controller beingturned off, and the engine ceasing operations, The engine controller 180signals the autonomous sensor system 190 to begin operating. Uponreceipt of the signal, the autonomous sensor system 190 beginsmonitoring in an “Autonomous Monitoring Begins” step 220.

Once the engine controller 180 confirms that the autonomous monitoringsystem 190 has begun monitoring the outputs of the sensors 160, 170. Theengine controller 180 switches the engine off, and the controller 180itself switches off in an “Engine Controller and Engine Switch Off” step230.

The autonomous monitoring system 190 continues monitoring the sensoroutputs in a “monitoring” step 240. In some examples, the monitoringincludes gathering of raw data and correlating the raw data with a timestamp. In other examples, the monitoring further includes comparing theraw data to one or more preconfigured thresholds to determine theoccurrence of a potentially hazardous event using the local processor194. When such an event is detected, the occurrence is logged in a logfile including a start time and an end time of the event. The log fileis stored in the local memory 192 until the engine controller 180requests the log file in a later step.

In some examples, the aircraft including the engine 20 can be parked fordays or weeks at a time. The autonomous monitoring system 190 continuesto monitor in the monitoring step 240 for the full duration of the offtime.

When a user, such as a pilot, wishes to engage the engine, the enginecontroller 180 begins initialization of the engine in an “EngineInitialization Begins” step 250. The engine initialization includes apowering on of the engine controller 180. The engine controller 180 thenengages in pre-flight checks to ensure that all engine systems arefunctional prior to starting the engine.

During the pre-flight checks, the engine controller 180 queries theautonomous sensor system 190 for sensed data that occurred during theoff time. In response to the query, the autonomous sensor system 190provides the engine controller 180 with the stored data. In exampleswhere the autonomous sensor system 190 stores raw data, the raw data isprovided to the engine controller 180, along with a time correlation,and the engine controller 180 analyzes the raw data to determine if anypotentially damaging conditions occurred. By way of non-limitingexample, potentially damaging conditions that could be detected includean oil inlet pressure falling below a minimum threshold value, and ashaft rotational speed exceeding a maximum value. When such an event isdetected, the engine controller 180 can determine that the engine shouldundergo maintenance before being operated, and the initializationsequence provides an error to the operator and stops.

In alternative examples, the autonomous sensor system 190 pre-analyzesthe data using a local processor 194, and the engine controller 180 isprovided with data relevant only to potentially damaging conditions. Insuch an example, the engine initialization time is reduced due to thedecreased analysis required to be performed during the initialization.

In yet further examples, the engine controller 180 can analyze the datafrom the autonomous sensor system 190 to determine if there are any timeperiods during the shutdown where data was not gathered from the sensors160, 170 for at least a minimum time period. If there are any such timeperiods, or gaps, the engine controller 180 can determine that theautonomous sensor system 190 was unable to monitor the system for theduration, and that the engine should undergo maintenance before beingoperated.

After the data has been fully analyzed, and the remainder of theinitialization sequence has been completed, the engine begins operating,and the autonomous monitoring system 190 ceases operations in an “EngineStarts” step 270. While the engine is operating, the power input to thepower storage device 196 provides power to the power storage device 196,and the power storage device 196 is charged up to full power.

It is further understood that any of the above described concepts can beused alone or in combination with any or all of the other abovedescribed concepts. Although an embodiment of this invention has beendisclosed, a worker of ordinary skill in this art would recognize thatcertain modifications would come within the scope of this invention. Forthat reason, the following claims should be studied to determine thetrue scope and content of this invention.

1. An engine health monitoring system comprising: an engine componentincluding a sensor system configured to monitor at least one parameterof the component; an autonomous monitoring system coupled to the sensorsystem and configured to receive and store the at least one monitoredparameter while an engine controller is unpowered; and the enginecontroller is communicatively coupled to the autonomous monitoringsystem.
 2. The engine health monitoring system of claim 1, wherein theautonomous monitoring system includes a power source configured toprovide operational power to the autonomous monitoring system.
 3. Theengine health monitoring system of claim 2, wherein the power source isconnected to an on-board generator of an aircraft.
 4. The engine healthmonitoring system of claim 2, wherein the power source includes an inputconfigured to be connected to a ground based power supply.
 5. The enginehealth monitoring system of claim 1, wherein the sensor system iscommunicatively coupled to the engine controller.
 6. The engine healthmonitoring system of claim 1, wherein the engine component includes abearing oil supply, and the sensor system includes an inlet pressuresensor.
 7. The engine health monitoring system of claim 6, wherein thesensor system includes an ambient pressure sensor.
 8. The engine healthmonitoring system of claim 7, wherein the inlet pressure sensor and theambient pressure sensor are the same sensor.
 9. The engine healthmonitoring system of claim 1, wherein the engine component includes ashaft and the sensor system includes a rotational speed sensorconfigured to detect a rotational speed of the shaft.
 10. The enginehealth monitoring system of claim 1, wherein the autonomous sensorsystem includes a local memory, a local processor and a local powerstorage device, the local processor being configured to: receive sensordata from the sensor system; correlate the received sensor data with atime at which the sensor data was generated; and store the sensor datain the local memory.
 11. The engine health monitoring system of claim10, wherein the local processor is further configured to pre-process thereceived sensor data and determine the occurrence of potentiallydamaging conditions.
 12. The engine health monitoring system of claim10, wherein the autonomous sensor system is further configured tocommunicate stored sensor data to the engine controller during an engineinitialization.
 13. A method of monitoring the health of a gas turbineengine comprising: sensing at least one of an inlet oil pressure and ashaft speed while a gas turbine engine is off; storing the sensed valuesof the at least one of an inlet oil pressure and a shaft speed in alocal memory of an autonomous monitoring system; and reporting thestored sensed values of the at least one of said inlet oil pressure andsaid shaft speed to an engine controller during an engineinitialization.
 14. The method of claim 13, further comprising analyzingthe reported stored sensed values using the engine controller during aninitialization of the engine, and halting the initialization of theengine in response to a determination that at least one componentoperated in a potentially damaging condition based on the sensed values.15. The method of claim 14, further comprising the engine controllerdetermining that a shaft operated in a potentially damaging condition inresponse to a sensed rotational shaft speed exceeding a maximumthreshold while the engine is off.
 16. The method of claim 14, furthercomprising the engine controller determining that a shaft operated in apotentially damaging condition in response to a sensed inlet oilpressure falling below a minimum threshold while the engine is off. 17.The method of claim 13, further comprising charging a local powerstorage device of the autonomous monitoring system while said engine isoperating.
 18. The method of claim 13, further comprising correlatingthe stored sensed values of the at least one of an inlet oil pressureand a shaft speed with a time at which the value was sensed using alocal processor of the autonomous monitoring system, and storing thetime correlation in the local memory.
 19. The method of claim 18,wherein reporting the stored sensed values of the at least one of saidinlet oil pressure and said shaft speed to the engine controller duringan engine initialization further includes reporting the time correlatedto the engine controller.